Calc's financial or business functions use the b prefix key followed by a shifted letter. (The b prefix followed by a lower-case letter is used for operations on binary numbers.)
Note that the rate and the number of intervals given to these functions must be on the same time scale, e.g., both months or both years. Mixing an annual interest rate with a time expressed in months will give you very wrong answers!
It is wise to compute these functions to a higher precision than you really need, just to make sure your answer is correct to the last penny; also, you may wish to check the definitions at the end of this section to make sure the functions have the meaning you expect.